The 64 horses allowed by plan require 768 AUMs per year and the HMA covers 11,724 acres, so the aimed-at stocking rate is 5.5 wild horses per thousand acres, considerably higher than the target rate across all HMAs of one wild horse per thousand acres.
The land must be able to produce at least 65.5 AUMs per year per thousand acres to support the Sands Basin horses.
This means the horses receive more forage than the ranchers!
The percentage of the allotment occupied by the HMA is unknown and the Draft EA may be months away but the forage assigned to livestock inside the HMA has to be less than or equal to 558 AUMs per year.
The allotment must be able to produce at least 41.1 AUMs per year per thousand acres to satisfy the ranchers, enough to support 3.4 wild horses per thousand acres.
The carrying capacity of the HMA, neglecting wildlife, would be 5.5 + 3.4 = 8.9 horses per thousand acres, assuming that forage is evenly distributed across the allotment.
The True AML would be 8.9 × 11,724 ÷ 1,000 = 104, the number of horses the HMA could support if it was managed principally for them.
The horses displaced from the HMA by permitted grazing would be the difference between the True AML and current AML, 104 – 64 = 40, or 3.4 × 11,724 ÷ 1,000.
The current size of the herd is unknown.